The present invention relates to a method of and apparatus for teaching an operation to an industrial robot and, more particularly, to an operation teaching method and apparatus suitable for industrial robots which are intended to be moved to a plurality of positions and to perform the same task at these positions.
Generally, industrial robots are fixed and perform tasks on works which are disposed within the reaches of the industrial robots. In the case where the works are of the same configuration, it is preferred from the view point of the working efficiency of the robot and the labour saving effect that the content of the operation taught to the robot for one of the works is memorized and reproduced at each time of operation to enable the robot to perform the same task on a plurality of works of the same configuration. This control method is generally referred to as a "teaching and playback control method" and a typical example of this method is disclosed in U.S. Pat. No. 3,920,972.
In recent years, the kinds of industrial robots are so diversified and there is an increasing demand for industrial robots which can perform tasks on the works installed on large structures which are difficult to move or on the works installed inside of box-shaped structures. In order to cope with this demand, it is necessary to take a suitable measure for moving the robot to the position of the work and to fix the same at this position. In the system in which the industrial robot has to be moved to different positions, it is impossible to adopt the above-mentioned teaching and playback control method which is designed for an industrial robot which is intended to perform a task at fixed position. Namely, assuming that the industrial robot first performs the task on a work at a first position and then moves to a second position where it performs the same task on the new work, it is quite difficult to realize in the second position the same positional relationship between the robot and the work as that attained in the first position. It is, therefore, impossible to effect the desired task on the work at the second position by reproducing the content of the operation taught in the first position. Consequently, it is necessary to teach the content of the operation again to the robot after the robot is moved to the second position.